(i) Field of the Invention
This invention relates to a corner which is specially adapted to provide a frame that will provide not only a pleasing appearance when assembled but also can be easily assembled or disassembled by anyone.
(ii) Description of the Prior Art
Anyone wishing to frame a picture, diploma or similar article is presently met with the problem of obtaining a proper size frame and mounting the object to be framed within it. In most instances this requires the assistance of a skilled commercial framer who will be able to cut the frame to proper size from wooden molding elements available to him, assemble it with nails and/or glue and then mount the object to be framed within it. An additional step of wedging the article within the frame evenly is frequently necessary. As is obvious, many people are not able to construct such frames because of lack of knowledge as to how to build a frame, no access to the necessary materials or inability to obtain or use the required tools. For those unskilled in such work, the frame when assembled by them lacks attractiveness, is weak and frequently separates at the joints.
Picture frames made from extruded aluminum moldings have also been used in the past. With such moldings, it is customary to provide a clamping assembly for interconnecting the mitered ends of the moldings in the frame. These picture frames often are available in unassembled kit form. The most common technique for assembling the picture frame sections into the complete frame includes the provision of channels on the rear surface of each of the frame sections, with the channels of adjacent sections in the corners of the frame meeting in L-shaped configuration. Typically, the adjacent ends of the frame sections have been assembled, to form a corner of the frame, by placing an L-shaped bracket at each corner of the frame so that each leg of the bracket extends into the channel of one of the adjacent frame sections. Each of the bracket legs is secured to its associated framing section by suitable locking means, usually a screw which is urged firmly against the rearwardly facing, inner surface of the channel formed on the rear surface of each framing member.
While the foregoing technique has been used widely, it does have some disadvantages. For example, the joint at the adjacent ends of the frame sections tend to loosen with time. This may be the result of the relatively soft character of aluminum which is used typically for the extruded frame sections. Additionally, because frames of the type described may be assembled and disassembled with relative ease, these frames often are used repeatedly to frame a number of different pictures. Because the screws which ordinarily bear firmly against the rearwardly facing surface of the aluminum channel tend to mar the channel and form depressions in the channel, the surface of the channel becomes irregular which reduces the effective holding power of the screws. This aggravates the inherent difficulty of typical prior devices which, even when unmarred by repetitive tightening of the screws, tends to make a poor and sometimes loose joint at the corners where the adjacent frame sections meet.
Many proposals have been offered to overcome such problems.
Canadian Pat. No. 594,004 issued Mar. 8, 1960 to L. I. Thompson merely discloses a picture frame construction involving the use of "L"-shaped members at the corner, cooperating with projections in the interior of the hollow frame members, with screws engaging the members and holding them together.
Canadian Pat. No. 881,000 issued Sept. 14, 1971 to Frameguild discloses a picture frame construction having the "L"-shaped corner members and screws to force the upper portion of the hollow frame. In accordance with that patent, a readily assembled and disassembled frame is provided with great strength and rigidity by the use of a plurality of side members in combination with simple locking and supporting means at the corners of the frame. In such frame, each side member is provided with an undercut channel at each end. A locking joint with portions angled at right angles is slipped into the undercut channels of adjoining side members, thus bringing the side members together in the proper relationship. Because the ends of each side member are usually beveled, their joinder forms a mitered joint. Once the locking joints place the side members in proper relationship, means associated with the locking joints are used to wedge, or otherwise firmly lock, the joints into the undercut channels. At this point the side members are not only correctly aligned but firmly fastened to each other. When all four sides of the frame are thus locked together, the resulting frame is not only rigid and strong but is attractive.
Canadian Pat. No. 925,292 issued May 1, 1973 to Artistic Woodwork relates to spaced-apart "L"-shaped members engaging, by means of screws, both faces of a frame flange. In such patent, a picture frame is provided which comprises a series of interconnected molding pieces mitered at their free ends to form a picture frame. The molding pieces have a picture retaining channel on their inwardly directed side and a clamping channel in their back surface. The clamping channel has a pair of diametrically opposed rails, one on each side wall of the clamping channel, and a clamping assembly in the channel extends between each of the interconnected molding pieces. The clamping assembly has opposed jaws which grip with the rails of the clamping channel to maintain the picture in a set up position.
Canadian Pat. No. 988,298 issued May 4, 1976 to Arlington Aluminum relates to a corner construction in which a screw inserted at a 45.degree. angle expands the corner interlocking square bars to hold the frame together.
Canadian Pat. No. 1,035,952 issued Aug. 8, 1968 to H. Neilsen provides a corner joint in which the "L"-shaped member is actually screwed into the "L"-shaped bearing plate which is urged into frictional engaging contact with the frame. In that patent, the invention includes the forming of the L-shaped bracket in cooperation with the configuration of the channel which receives the bracket so that when the fastening means, such as the screws of the bracket are tightened, cantilevered wall extensions of the frame sections will twist or cant slightly inwardly to cause the beveled corners of the frame sections to be urged snugly against each other, thus enhancing the front appearance of the frame by avoiding gaps at the corner and also providing a tighter fit. In one embodiment this is achieved by forming selected surfaces of the channel at a slight bevel. In another embodiment, the L-shaped brackets have a beveled and/or wedge-shaped cross-section which cooperate with the channel configuration to achieve the desired effect.
Canadian Pat. No. 1,041,762 issued Nov. 7, 1978 to O. B. Kapstad provides a corner construction in which the "L"-shaped corner joint has a pair of spring gripping tongues thereon.
Canadian Pat. No. 1,092,352 issued Dec. 30, 1980 to General Systems Research Ltd. provides a corner construction in which the "L"-shaped members are held by screws between two spaced-apart webs of the frame.